m8554

I have an 03 LS with stock 225/55-17 tires.
I thought increasing to a 60 series sidewall would soften the ride. This would increase the tire diameter by about 1"
I was told not to change the overall diameter of the tire as it would affect the speedometer and possibly other computer driven parts of the car.
I see many CL members increasing their tire and wheel size to 20" or more. What effect does this have on the car?
I know I could put a set of 16" wheels on the car but was curious if using the original 17" with a wider sidewall was OK.
Anyone try this?

motohide

As long as the tire fits inside the fender, the concern for effects on the speedometer and other devices are minimal with using tires that are larger or smaller in diameter.

The tire on all four ends however should be very close in diameter as the LS430 and most modern cars do check rotational speeds for tire inflation sensors.

The speedometer and any calibration of vehicle speed necessary for engine, drive-train and navigation will be affected slightly, but as long as all four tires remain similar in speed, there should be no computer generated malfunction errors.

The difference in speed metering and actual speed is only off by the percentage of the diameter difference of the tires.

I use a 245/40-20 Front and 275/35-20 Rear and diameter is very close. Tire inflation sensor tripped at first install but after reset it is behaving normally. Speedometer, navigation, and cruise control is functioning normally with minimal error for speed reading...at least not enough to make speedometer reading unusable for normal driving around town or freeways.

The LS430 is a VERY quiet car inside though, and changes you make to tire tread pattern, sidewall stiffness or size, can all make for a noisy tire in the cabin however, if you are not careful with the selection.

AlexusAnja

What are you going to do? A 215/60-17? The speedo will be slower than you are actually travelling. Really, I would go down to 16" for a softer ride if that's what you're looking for. I have 16" for winter and it makes the boaty LS even more boaty.

Those that have gone to 20" basically keep their diameters the same by getting smaller aspect ratio tires. It makes the ride harsher by allowing for less sway and firmer ride.

AlexusAnja

Another thing, the "center" number is just an aspect ratio of percentage of sidewall to width of tire. You really can't "increase" the diameter by more than 1" without offsetting the speedo. so if you're really look for a softer ride, you almost have to go down to a 16" rim.

campisi

Your computer won't even notice a 1 or 2% difference in tire diameter (think about this - when your brand new tires wear towards the end of their life the diameter shrinks by probably up to 2 inches or more just from tread wear, notice your computer malfunctioning then?). Here's a link to a decent tire size calculator that will calculate differences from your stock to your proposed new tire and/or rim combination - it also estimates rim width needed for a particular tire size:

http://www.1010tires.com/tiresizecalculator.asp

m8554

Since I need new tires anyway, I was thinking of going to a 225/60-17. According to the tire comparison chart, it would be a 3% change and I wouldn't have to buy new wheels. I don't know if it would have any problems with rubbing. Is anyone running this tire size that can comment?

Kansas

m8554, what are you setting your tire pressures to? Tire pressure can make a huge difference in ride quality. The recommended tire pressure in my older (2000) LS is only 29 psi. Try setting the tire pressures to the recommended pressures shown on your driver side door jam.

It may be all in my head but I think I can detect a difference in ride quality as tires age and tread wears down. Maybe new tires in the correct OEM 225/55-17 size will "feel" better to you than the ones you have now that are nearly worn out.

And some tires ride much more harshly than others. The long wearing Michelin Primacy MXV4 H-rated all season tires I bought from Costco a couple of months ago have a far more cushy ride than the Z-rated Bridgestone RE750 "ultra high performance" category summer tires I used for the past three years.

I highly recommend the Michelin Primacy MXV4 as others on this forum have. If you have a Costco nearby, they are "on sale" again ($70 off a set of 4). $70 will more than pay for the annual Costco membership fee and you will get a rebate at the end of the year. (Full disclosure -- I am a Costco shareholder but only because it's a damned good company.)

I know that Costco carries the MXV4 in 225/55-17 because they accidentally gave me one in that size when I bought the set of 225/60-16 for my 00 LS. My local Lexus dealer was not amused when he attempted to install the 17" tire on one of my 16" wheels but Costco delivered the correct size tire to the Lexus dealer within an hour.

m8554

I'm running 30 psi. My last car was a 99 LS with 16" wheels and I guess I'm just used to the ride with the old car that was smoother. Thats why I think I can get the same ride with the 17" wheels by using a 60 series sidewall thats about a half inch taller than the 55 series. 5.31" for the 60 vs 4.97" for the 55. The comparison specs are listed below. Just need to know if anyone is running them now and if all is OK.

Stock Tire - 225/55R17 >Search Tires Tire 1 - 225/60R17 >Search Tires
Section Width: 8.85 in
Section Width: 8.85 in

Rim Diameter: 17 in
Rim Diameter: 17 in

Rim Width Range: 6 - 8 in
Rim Width Range: 6 - 8 in

Overall Diameter: 26.74 in
Overall Diameter: 27.62 in

Sidewall Height: 4.87 in
Sidewall Height: 5.31 in

Radius: 13.37 in
Radius: 13.81 in

Circumference: 84.00 in
Circumference: 86.77 in

Revs per Mile: 777.8
Revs per Mile: 753.0

Actual Speed: 60 mph
Speedometer1: 58.0 mph

Speedometer Difference: - Speedometer Difference: 3.293% too slow
Diameter Difference: - Diameter Difference: 3.19%

m8554

Anyone running this size? 225/60-17